Biology subjects

Hojlund, A.

Publications and source records attributed to Hojlund, A..

3 recordsLinked to original sources

bioRxiv2019

Electromagnetic mapping of the effects of deep brain stimulation and dopaminergic medication on movement-related cortical activity and corticomuscular coherence in Parkinson’s disease

BackgroundParkinsons disease (PD) is a debilitating neurodegenerative disorder. PD can be treated with deep brain stimulation (DBS) when dopaminergic medication is no longer a viable option. Both treatments are effective in improving motor symptoms, however, their underlying mechanisms are not fully elucidated yet.\n\nObjectivesTo study the effects of DBS and dopaminergic medication treatments on cortical processing and corticomuscular drive during movements.\n\nMethodsMagnetoencephalography (MEG) was recorded in 10 PD patients and 10 healthy controls, performing phasic hand contractions (hand gripping). Measurements were performed in DBS-treated, untreated and dopaminergic-medicated states; healthy controls received no treatment interventions. Participants performed phasic contractions with their right hand, recorded with electromyography (EMG). Our measures of interest were beta (13-30 Hz) corticomuscular coherence (CMC) and low-gamma (31-45 Hz) power. We used Bayesian statistics on summary values from sensor space data, and we localized the sources of the effects of treatments on beta-CMC and low-gamma power using beamforming.\n\nResultsIn PD patients, DBS led to reduced CMC values, whereas dopaminergic medication increased beta-CMC values (localized to contralateral M1) to even higher levels than the controls. DBS, on the other hand, increased low-gamma power (localized to M1) compared to controls and to other conditions. Yet both treatments had similar beneficial effects on the patients motor symptoms evaluated by UPDRS-III.\n\nConclusionDespite comparable improvements from both treatments on motor symptoms, DBS and dopaminergic medication seem to have different effects on motor cortical function. This indicates that the treatments undertake different functional strategies to improve PD symptoms.

neuroscience↗

bioRxiv2019

Poorer auditory sensitivity is related to stronger visual enhancement of the human auditory mismatch negativity (MMNm)

Multisensory processing facilitates perception of our everyday environment and becomes particularly important when sensory information is degraded or close to the discrimination threshold. Here, we used magnetoencephalography and an audiovisual oddball paradigm to assess the complementary role of visual information in subtle pitch discrimination at the neural level of participants with varying levels of pitch discrimination abilities, i.e., musicians and nonmusicians. The amplitude of the auditory mismatch negativity (MMNm) served as an index of sensitivity. The gain in amplitude resulting from compatible audiovisual information was larger in participants whose MMNm amplitude was smaller in the condition deviating only in the auditory dimension, in accordance with the multisensory principle of inverse effectiveness. These findings show that discrimination of even a sensory-specific feature as pitch is facilitated by multisensory information at a pre-attentive level, and they highlight the importance of considering inter-individual differences in uni-sensory abilities when assessing multisensory processing.

neuroscience↗

bioRxiv2019

Domain-relevant auditory expertise modulates the additivity of neural mismatch responses in humans

It is unknown whether domain-relevant expertise is associated with more independent or more dependent predictive processing of acoustic features. Here, mismatch negativity (MMNm) was recorded with magnetoencephalography (MEG) from 25 musicians and 25 non-musicians, exposed to complex musical multi-feature and simple oddball control paradigms. Deviants differed in frequency (F), intensity (I), perceived location (L), or any combination of these (FI, IL, LF, FIL). Neural processing overlap was assessed through MMNm additivity by comparing double- and triple-deviant MMNms ("empirical") to summed constituent single-deviant MMNms ("modelled"). Significantly greater subadditivity was present in musicians compared to non-musicians, specifically for frequency-related deviants in complex contexts. Despite using identical sounds, expertise effects were absent from the simple paradigm. This novel finding supports the dependent processing hypothesis whereby experts recruit overlapping neural resources facilitating more integrative representations of domain-relevant stimuli. Such specialized predictive processing may enable experts such as musicians to capitalise on complex acoustic cues.

neuroscience↗